Washington Nationals third baseman Ryan Zimmerman can't make the tag...

Washington Nationals third baseman Ryan Zimmerman can't make the tag in time as New York Mets' Ronny Cedeno gets to third on his hit, during the fourth inning of a baseball game at Nationals Park. (Aug 19, 2012) Credit: AP

WASHINGTON -- The trains kept moving in opposite directions this weekend. The Mets quite literally headed north after Sunday's 5-2 loss at the hands of the Nationals, but they quite metaphorically continued heading south, losing yet another series in this post-All-Star break funk that hasn't ended.

The Mets are 11-24 since the break. It didn't help to visit the Nationals, who are now 26-12 since the break -- including 7-2 against the Mets -- and continuing to roll along in the National League East driver's seat.

The Mets failed often when it mattered most Sunday. After a 2-hour, 25-minute rain delay, Nationals starter Gio Gonzalez (16-6) did not look his freshest, but the Mets were not at their most clutch: they had runners on in each of the first seven innings but squeaked across just one run, on Jason Bay's dribbler to short to bring in Ike Davis in the sixth.

They were 1-for-11 with runners in scoring position and stranded 10 total, the only productive hit an eighth-inning single by Kelly Shoppach to score Ronny Cedeño to make it a three-run game.

"You've got to get key hits," manager Terry Collins said. "We sat here all through the first half [of the season] talking about how many key hits we got. We're not getting them right now."

On the flip side, the Nationals converted when given the chance against Jeremy Hefner (2-5), the Mets righthander added to the new six-man rotation. Danny Espinosa hit a two-run home run in the second inning, an opposite-field shot to left on a curveball. Bryce Harper tripled in a run with a shot to the right-center gap in the third, then scored on Ryan Zimmerman's single.

Harper followed with a solo homer to lead off the fifth, his second home run of the three-game series and third -- out of 12 total -- against the Mets this season.

"You're going to make mistakes. Sometimes you get away with them, sometimes you don't," said Hefner, who allowed five runs and eight hits in five innings. "Today, it seemed like I didn't get away with any. They're a good team."

The Mets' hitters continued to swoon as the team scored fewer than three runs for the fourth time during their 2-4 road trip. David Wright had two singles Sunday, but he finished the weeklong trip just 5-for-22 with no RBIs, the six-game streak without an RBI tying his longest of the season.

Davis, who came in 3-for-5 with a home run against Gonzalez, left two men on in each of his first two trips to the plate. Bay went 0-for-4, dropping his already minuscule average to .151.

The Mets host the Rockies and Astros this week, the NL's two worst teams. If these six games can't stop the Mets' slide, it won't end until the season does.

"We're not exactly playing great," Collins said. "We can't let up. This is what happens when you have to grind it out and grind out every day."

Notes & quotes: SS Ruben Tejada did not start, with Collins noting that the Mets are in a stretch of playing 12 consecutive days. "He'll play every day next week," Collins said of Tejada, who had his streak of hitting in 16 straight road games snapped Saturday. Tejada flied out to center as a pinch hitter in the sixth . . . Daniel Murphy was ejected after getting caught looking as a pinch hitter in the eighth . . . R.A. Dickey (15-4) starts Monday night at Citi Field against the Rockies.

SUBSCRIBE

Unlimited Digital AccessOnly 25¢for 6 months

ACT NOWSALE ENDS SOON | CANCEL ANYTIME